When an IC or CPU which is mounted on a mother board is operated, it produces heat. In order to prevent the IC or CPU from being burned out, heat must be quickly carried away during the operation of the IC or CPU. Heat sink and electric fan are commonly used for this purpose. FIG. 1 shows a heat sink mounting arrangement according to the prior art. As illustrated, the heat sink 12 is closely attached to the top side wall of the CPU 11 above the mother board 10, and screws 13 are mounted in corner mounting holes 121 on the heat sink 12 and threaded into respective screw holes 101 on the mother board 10 to secure the heat sink 12, the CPU 11 and the mother board 10 together. This heat sink mounting arrangement has drawbacks as follows:
1. It is complicated to process holes on the heat sink and screw holes on the mother board. The procedure of using screws to fasten the heat sink to the mother board is also complicated. PA1 2. The inner threads of the screw holes wear quickly with use. The screws become loosened when the inner threads of the screw holes are damaged, thereby causing the heat sink unable to be closely attached to the surface of the CPU. PA1 3. Because the screws are rigid elements and fastened to the heat sink in four corners, heat cannot be effectively transmitted from the CPU to the heat sink when the mother board deforms.